Index: lib/redcloth.rb
===================================================================
--- lib/redcloth.rb	(revision 1227)
+++ lib/redcloth.rb	(working copy)
@@ -785,7 +785,7 @@
             atts << " title=\"#{ title }\"" if title
             atts = shelve( atts ) if atts
             
-            external = (url =~ /^http:\/\//) ? ' class="external"' : ''
+            external = (url =~ /^https?:\/\//) ? ' class="external"' : ''
             
             "#{ pre }<a#{ atts }#{ external }>#{ text }</a>#{ post }"
         end